The United States is doing “everything in [its] power” to end the bloodshed in the Gaza Strip, Secretary of State John Kerry said Wednesday, as he kept up contacts with regional leaders.

“Our concern is to have a legitimate ceasefire and see if we can find a way to stop the conflict and killing so we can get to the real issues that are underlying it,” Kerry told reporters as he met his counterpart from Luxembourg.

“And we’re doing everything in our power,” said Kerry, adding that he has been speaking to Prime Minister Benjamin Netanyahu and Arab officials.

Egypt’s efforts to broker an end to the violence, which has killed 220 Palestinians, collapsed on Tuesday. The terror group Hamas, which rules Gaza and has fired more than 1,200 rockets into Israel, rejected the proposal on the grounds that it was not included in talks.

The State Department said that Kerry in the past day has spoken to the foreign ministers of Egypt as well as Qatar and the United Arab Emirates, which are seen as holding influence with Hamas, and to Arab League Secretary General Nabil al-Arabi.

Kerry, who has spent much of his tenure seeking unsuccessfully to negotiate a lasting peace agreement, is open to returning to the region if he would be useful, State Department spokeswoman Jen Psaki told reporters.

Psaki declined to criticize US ally Israel over the latest violence, in which four children died and several others were wounded in an apparent naval bombardment of a beach in Gaza City, saying the United States was not in a position to confirm the situation on the ground.

But Psaki said: “The loss of lives for children and individuals in Gaza is horrific and is a tragedy, and that’s why we’re so focused on bringing an end to the violence.”